LED Battery life question

Newbie here with a newbie question.



I have a small round keychain LED, it's a Rayovac that I got at Wal-Mart a couple years back. I cannot find this particular model online anywhere so I assume it is discontinued.



The light runs on two 2016 cell batteries but I noticed after I disassembled the light to put new batteries in that it can easily be rigged to run on ONE 2016 battery instead of two. When burning on only one battery the light appears about half the brightness as on both batteries.

My question is would it be a good idea to try and run the flashlight on only one battery rather than the way it is designed to be ran? Would I get double the runtime since the battery is powered lower or would I simply damage the bulb?

Like I said it isn't super bright on just one battery (prob equiv to a Maglite Solitaire) but if I could get forty or fifty hours off two batteries that way instead of ten or twelve ideas it might be worth the dimness.

Please chime in with any advice and its a pleasure to be aboard the forum. Very interesting place

Wp

Yes, by removing one battery, you are cutting the voltage in half, so your brightness will be diminished by half, if that amount of brightness is sufficient for you. you will get double the battery life by running it at half voltage (one battery), then swapping the battery once over the lifespan of the two batteries.

In (hopefully simpler terms) one battery at 1v will last as long as two batteries together @ 2v

Stop being a tight wad,stick 2 back in it.

If you are ok with the brightness of one battery, use one 2032. It is the same diameter and it is the thickness of two 2016s. Some coin cell light come this way. You will get VERY long runtimes in this configuration. It won't hurt the light one bit.

If your "eyes" tell you it is half as bright, then you can count on something closer to 1/10th to 1/4th as bright. Just depends on your personal perception. I'd guess it's closer to 1/10th in this case. If you can run it on a single cell instead of 2, you will probably get 10-100X the original battery life.

Enjoy.

cbutters said:

Yes, by removing one battery, you are cutting the voltage in half, so your brightness will be diminished by half, if that amount of brightness is sufficient for you. you will get double the battery life by running it at half voltage (one battery), then swapping the battery once over the lifespan of the two batteries.

In (hopefully simpler terms) one battery at 1v will last as long as two batteries together @ 2v

Click to expand...

I'd like to clarify on both counts.

1. CR2016 batteries are nominally 3v. Two in series are nominally 6v. That nominal ("Open-circuit") voltage drops as you draw current from the battery. Drawing just 20 mA to light a 5mm white LED quite brightly drops the voltage the cells can deliver, to around 3.2 or 3.4v. A single 2016 cell will give 3v open circuit, or a bit less than that to give about 5 mA to that same LED. The current and light output have gone down to about 25%, but the voltage is going to be around 2.8 or 2.9v. NOT half.

2. The CR2032 has roughly twice the capacity as the CR2016 (Those numbers are their Diameter and Thickness, in mm - 20mm diameter, and 1.6 or 3.2mm thick). The larger capacity and lower current delivery of a CR2032 vs 2 CR2016 will give the first one a MUCH longer runtime, at a not-very-dimmer looking brightness. I'd estimate over twice as long to get to annoying dimness.